Drop-out fuse constructions



April 28, 1959 G. R. MCCLOUD 2,884,500'

DROP-OUT FUSE.l CONSTRUCTIONS Filed April '7. 1958 4 sheets-sheet 1 i z'\ safs \4 3f? INVENTO R. Geom?. R. MC CLouD Fx 6 BY April 28, 1959 G. R. MGcLoUD DROP-OUT FUSE CONSTRUCTIONS 4 Sheets-Sheet 2 Filed April 7. 1958 w m M xNvENToR. GEORGE R. McCLoun BY mmlzw A11- New April 28, 1959 G. R. McLoUD DROP-OUT FUSE coNs'rRucTxoNs 4 Sheets-Sheet 3 Filed April 7. 1958 INVENTOR. GEORGE R McCLouo April 28, 1959 G. R. MccLoUD 2,884,500

l DROP-OUT FUSE coNsTRucTroNs Fliled April '7, 1958 4 Sheets-SheetI 4 1 2 K N' a l o INVENTOR. GEORGE RMCLouD A-rroRNEY United States Patent O DROP-OUT FUSE CONSTRUCTIONS George R. McCloud, Cudahy, Wis., assignor to McGraw- Edson Company, Milwaukee, Wis., a corporation of Delaware Application April 7, 1958, Serial No. 726,787

11 Claims. (Cl. 20D-114) This invention relates to drop-out fuse constructions.

In drop-out fuse constructions as heretofore made, it is the usual practice to provide projecting portions carried by the lower end of the fuse tube and interlocked with a flip-out lever to normally hold the fuse tube in operative or service position. The fuse link extends from the upper end of the fuse tube out of the open lower end of the fuse tube and around the nip-out lever, and spring means are provided biasing the tlipaout lever towards releasing position. When the fuse link is ruptured the flip-out lever operates to extract any remaining portion ofthe fuse link from` the fuse tube and at the same time to release the projecting members or pins of the fuse tube from engagement with the Hip-out lever so that the fuse tube can drop downwardly out of service position.

A primary purpose of this invention is to provide time delay means for a drop-out fuse construction which consists of a very simple mechanism independent of dash pots, escapement mechanisms, or other devices of this type, but which instead consist primarily of rocking cam means which restrains the fuse tube in service position a sufficient length of time to insure complete clearing of the fuse tube before the fuse tube is released for dropout motion. It has been found that where the fuse tube moves towards drop-out position before it has been completely cleared internally that an arc is produced between the upper contact of the fuse tube and the upper stationary contact. Ionization occurs and it frequently happens that there is an arc established between the two stationary contacts and ashover and possibly complete destruction of the apparatus thereby results. When ilashover occurs between the two stationary contacts or terminals of the cut-out, the device has failed to accomplish its intended purpose and the fault must be eliminated by some back-up device.

This invention eliminates any possibility of destruction due to arcing produced by motion of the fuse tube away from the upper stationary contact until sucient time has elapsed to insure clearing within the fuse tube.

Further objects are to provide a dropout fuse construction with time delay means and with an expendable top or cap and in which the expendable cap is arranged to be either blown completely free of the fuse tube or in which the expendable cap has a weakened portion which is blown off, or blown open, so that in either case the fuse tube is vented at both ends. In greater detail, further objects are to provide a fuse tube of the drop-out type in which an expendable cap is provided for normally closing one end of the fuse tube so that whether the fuse tube is mounted vertically or horizontally it has a normally closed end. Further, it will be noted that when the fuse tube is mounted horizontally and is vented at both ends that the normal `time delay due to the reaction from the gases discharging from one end only does not occur since it is balanced by the discharge from the other end of the fuse tube simultaneously, and, there- 2,884,500 Patented Apr. 28, 1959 ice fore a further specific object of this invention is to have the construction such that even where there is no normal reaction from the discharging gases that nevertheless there is the direct cooperation between the expendable cap and the time delay means so that the time delay means will function independently of any reaction due to the expelling of the gases from the fuse tube.

In the prior constructions it is necessary to rota-te the fuse tube axially until the projecting pins or members align with corresponding portions of the flip-out lever. Also with prior constructions there is a tendency for the device to stick when corrosion sets in or when any form of deposit forms on the coacting pins and flip-out lever thus increasing the friction at this point materially and sometimes interfering with the reliable operation of the device.

Further objects of this invention are to provide a drop-out fuse construction having a tlip-out lever which is provided with roller means engaging a collar carried by the lower portion of the fuse tube and preferably having a beveled lower surface so as to have a tendency to urge the ilip-out lever towards releasing position if so desired, the llip-out lever being provided with means engaging the collar and the beveled under surface thereof of the fuse tube.

Further objects of this invention are to provide a flipout lever with roller means so arranged that the fuse tube may be rotated inadvertently or otherwise about its longitudinal axis into any position as no requirement is made for aligning any projecting portions of the restraining member carried by the fuse tube with the interlocking portion of the ilipout lever.

More specifically objects of this invention are to provide a drop-out fuse construction in which the fuse tube is provided with a collar adjacent its lower end and the ip-out lever assembly is provided with roller means which engages the collar and which also engages cam means on the ilip-out lever. The roller means engaging the collar is free to rotate independently of the roller means engaging the cam portion of the flip-out lever, thereby providing a device which has the minimum of friction and which greatly reduces the probability of sticking due to corrosion or to any other cause.

Further objects are to use the set screws normally holding the collar, hereinabove mentioned, to the fuse tube so that these set screws may be allowed to project outwardly beyond the collar and align and interlock with slots formed in a portion of the adjacent structure to thus prevent rotation of the fuse tube about its longitudinal axis at the time that the screw cap at the upper end of the fuse tube is screwed into locking engagement with the disk head of the fuse link. Heretofore it has been the practice of the lineman to hold the tube in his glove during the time that the upper screw cap is tightened. If there should be any inadvertent rotation of the fuse tube about its longitudinal axis and if there is any sharp projecting portion on the fuse tube there is great likelihood of cutting the glove of `the lineman when the upper screw cap is tightened. This invention therefore eliminates that danger and provides means in a simple form of ta pered slots which receive `the projecting pins or screws of the fuse tube and interlock and guide them into narrower portions of the slots to thus hold or lock the fuse tube against rotation about its longitudinal axis so that there is no chance of cutting the glove of the lineman when the upper screw cap is tightened.

Further objects are to provide a very simple construction of restraining means for a drop-out fuse tube construction which is Very cheap to manufacture, which is reliable in operation and which has a minimum number of parts, and which develops a minimum amount of friction during operation.

Embodiinents of the invention are shown in the ac- ^c'inpafrying vdrawings in which:

Figure 1 is a sectional view through the housing and fuse tube assembly showing the fuse tube assembly in lservice or closed position.

Figure 2 is a sectional view of `the lower portion of the device showing the fuse tube in its down or fused position.

Figure 3 is a bottom view of the structure shown in Figure l.

Figure 4 is a line section on the line 4-4 of Figure l.

Figure 5 is a line section on the line 5-5 of Figure 1.

Figure 6 is a schematic view of the roller and cam means while the fuse tube is in its uppermost or revstrained position.

Figure 7 is a similar view of the roller and cam means when the fuse tube is released.

Figure 8 is a view corresponding to Figure 6 showing 'a further form ofthe yinvention with greater time delay.

Figure 9 is a view of the roller and cam means of Figure S in position corresponding to Figure 7.

Figure 10 isa further form of the invention corresponding to that shown in Figure 2.

Figure 1l is a still further form of the invention corresponding to that shown in Figure 2.

Figure l2 is a modification of the collar and fuse tube land 'the restraining roller means.

Figure 13 is a fragmentary sectional View showing how an expendable top or cap can be used.

Figure 14 is a view corresponding to a section on the line 14--14 of Figure 13.

Figure 15 is a further view partly in section showing an'expendable top or cap.

Referring to the drawings it will be seen that the device Vc't'vr'iprises an insulating housing such as porcelain l1 and a plastic or other type of door 2. The housing 1 carries the stationary contacts consisting of an upper 'contact assembly indicated generally by the reference character 3 and a lower contact assembly indicated generally by the reference character 4.

While a closed type of housing has been shown it is to be understood that the invention could be equally well adapted lto an open type cut out as the essence ofthe invention relates to the delay action before the drop-out and ythis delayed action could be Ysecured whether the device wasa closed'type of drcpLout or an open type of drop-out device. Each of the upper and lower stationary v`contact assemblies is provided with a conduct-or receivcollar 12 carried by the link is clamped between 'ing clamping 'member indicated generally by the reference characters 5 and 6 for the upper and lower stationary housing contact assemblies, respectively, the conductors extending into the housing through apertures 7 'and 8.

` The upper stationary housing contact is provided with a spring nger 9 which presses downwardly on a metal screw cap 10 of the upper terminal of the fuse tube 11, such screw cap being screwed on the threaded metal fuse tube 11. The fuse tube 11 is of ber or other suitable material in accordance with the usual practice. The head or disk 9 of the fuse the cap 10 and the collar 12 in the usual manner, and the lower portion or leader 13 Qof the fuse llink extends through the open lower end of which may be called 'cated generally by the the fusetube.

, The door 2 carries a'stationary lower contact assembly the stationary door contact, indireference character 14. This door 'contact'is provided with a sleeve 15 which is welded or otherwise secured to the side walls 16 of the U-shapcd `bracket 17, which is carried by the door, see Figures 1, 2

and '4. The tube 11 freely slides through the sleeve 15 and yprojects downwardly when the fuse link has blown. The door, however, remains closed since the stationary *contact 4 ofthe housing is provided with a pair of spring 'tigers 'I8 which engage the upper portion of the side walls of the bracket 17, see Figures 1, 2 and 4. The spring fingers 18 of the lower stationary housing contact extend into the depressed portions 19 of the bracket 17 and thus yieldingly hold the door locked in closed position. The door may be readily pulled outwardly and rocked downwardly to open position by means of the handle 2t? of the door 2, see Figure 1. The lower portion of the door is provided with a bracket 21 having projecting arms which are notched and tit over inwardly projecting pins 22 carried by the housing 1, see Figures 1 and 3.

The lower contact 14 of the door 2 has an inner wall, indicated by the reference character 23 which is provided with a yquick-acting leader clamping or fastening means 24 of a wellknown type, see Figures l and 2. The leader extends outwardly from the lower open end of the fuse tube 11 and over a flip-out lever or pivoted member 25, see Figures l and 2, which is spring pressed in a clockwise direction by means of the spring 26 and acts as a flip-out means for quickly extracting any remaining portion of the fuse link after the fuse link has blown.

It is to be noted that the lower portion of the fuse tube 11 is provided with a collar 27 which may be of metal or may be of plastic or other material or could be an integral part of the tube itself, and which has a beveled lower face 28 and may have a beveled upper face 29, see Figure 2. The collar 27 is locked to the fuse tube by means of diametrically opposed set-screws 30. These Vset-screws do not extend through the fuse tube, but merely engage the outer surface of the fuse tube 11 and lock the collar 27 rigidly in place. The collar need not be beveled in all forms of the invention as will appear later and as shown in Figure 12.

The screws 30 may, if desired, project outwardly beyond the collar, as shown in Figure 5, and are thus adapted to enter V-shaped notches 31 formed in the side wall 16 of the bracket 17, see Figure 2. The notches 31 are provided with parallel sided upper or straight portions 32, see Figures l and 2. The time delay will work just as well whether the screws are extended or not but inasmuch as the screws have to be used or some other type of fastening means for the collar, it is desirable to have the additional function performed by the screws preventing undesired rotation of the fuse tube as explained hereinabove.

When the tube is in service or closed position, as shown in Figure l, the set-screws 3G extend upwardly into the straight portion 32. of the notches in the side wall 16 of the bracket 17 and thus prevent the tube from turning. The purpose of this is to prevent twisting or turning of the fuse tube about its axis during refusing when the lineman is tightening the upper screw cap 10. The lineman otherwise would have to hold the fuse tube in his gloved hand and his glove might be cut or torn in the event there were any sharp portions projecting from the fuse tube. When, however, the fuse link has been threaded through the fuse tube and the fuse tube is held in its uppermost position by locking the fuse link leader beneath the quick acting locking member 24, it will be seen that any turning or rotation of the fuse tube `11 when the cap 1t) is being screwed down, is resisted by the engagement `of the pins 30 with the side walls of the notches 32 and thus no damage can come to the glove or hand of the lineman.

The fuse tube is held in service or upper position by the engagement of a roller assembly indicated generally by the reference character 33, consisting of a center roller 34 which is rigid with the pin or axle 35 and is pressed thereon, and a pair of rollers 36 which are revolubly mounted on the axle or pin 35 and are free to rotate thereon. The axle or pin 35 projects beyond the roller assembly 33 and its ends are positioned in slots 37 formedin the side walls 16 of the bracket 17, see Figures 2 and 5. The roller assembly, it will be seen from the description given hereinabove, is free to move inwardly away from the collar 27 to release the tube when the fuse link blows.

It lis not necessary for the ipper or for the guiding means to be carried by the lower contact as will appear hereinafter.

The roller assembly or what may be hereinafter called the roller or roller means is held in its tube-restraining position or tube-locking position, shown in Figures 1 and 5, by means of the cams or outer surfaces 38 of the cam means of the flipper or fuse link extracting lever 2S, see Figure 1. This will hold the roller assembly 33 in its outermost position or locking position. It is urged to the left or inwardly by means of the weight of the tube 11 and by means of the downward thrust of the spring finger 9 of the upper contact assembly, see Figure 1. Obvious- 1y any other type of spring for urging the fuse tube downwardly could be employed.

When the fuse link blows the fuse link is ruptured and expelled `from the fuse tube and the fuse link extracting member or flipper 25 quickly withdraws any remaining portion of the fuse link from the end of the fuse tube. The clockwise motion of the flipper 25 allows its cams 38 to move away from engagement with the end rollers 36 of the roller means and thus allows the roller means to move to the left, as viewed in Figures 1, 2 and 5, thus releasing the fuse tube and allowing it to drop downwardly.

It is to be noted that the upper stationary contact includes a portion, such as the spring finger 9, which follows the fuse tube downwardly and maintains contact with the upper Contact of the fuse tube until the fuse tube has been completely released by the cam means.

The cam means has an extended fuse tube restraining portion to provide a time delay to delay separation of the upper contact of said fuse tube from the upper stationary contact for a material length of time thereby providing ample time for the fuse tube to clear itself.

Attention is directed to Figures 6 and 7. In Figure 6 the position of the parts are shown when the fuse tube is in its uppermost or restrained position, In Figure 7 the position of the parts are shown when the fuse tube has been released and has dropped downwardly. It will be seen that the cam face 38 has its effective portion between the radial lines 39 and 40 which dene the angle A and this angle is a measure of the amount of time delay provided by the construction shown in the first form of the invention namely in Figures 1 through 7.

The line 27 is the outer line of the collar, and also 27 is the path traced out by the outer face of the collar 27 of the fuse tube 11 when it moves downwardly and is shown so as to indicate the position that the locking roller 33 must be in when the fuse tube is released after blowing of the fuse link. It is obvious that the restraining roller means 33 has to move so that it is tangent to line 27 as shown in Figure 7 in order to release the fuse tube for downward motion. Any slight motion downwardly that the fuse tube might make before release is taken up by the spring nger 9' of the upper stationary contact, see Figure 1 of the drawings, and thus contact is maintained between the upper contact of the fuse tube and the upper stationary contact until a complete clearing of the fuse tube has been accomplished. As stated, the angle A, see Figure 7, is the measure of the amount of time delay afforded by this construction.

It is obvious that the cam may have a longer or more extensive restraining cam face or edge portion as shown `at 38 in Figures 8 and 9 so as to provide a longer delay period as indicated by the angle B in Figure 9. Comparing the angles A and B, it will be seen that the angle B is materially greater than the angle A and consequently a greater time delay is afforded by the second form of the invention shown in Figures 8 and 9.

It is, of course, to be understood that the mass of the ipper and the strength of the spring as well as the weight of the tube all have some effect on the time delay but of a lesser extent than that hereinabove described.

Any desired time delay within the limits of the mechanism may be chosen as required. This time delay is obtained by purely mechanical means without the use of dash pots or their equivalent, or escapement mechanism or similar devices, but instead is obtained by very simple mechanical means as shown in Figures 6 to 9.

It will be seen that a very simple and very serviceable construction has been provided which is easy to operate and has very little tendency to stick or remain in locked position even if corrosion or any deposit should form on the structure. Also, it is to be noted that it is a very simple matter to assemble the mechanism and the structure itself is extremely simple, though highly serviceable 1n use.

The fuse construction may be a housed type as shown or an open type. In either case, it is to be noted that some sort of supporting means must be provided and that the fuse tube guiding means and the pivotally mounted Hip-out lever are, in reality, supported from the supporting means, so that as compared with the downwardly movable fuse tube, they are relatively stationarily mounted.

Further, it is to be understood that the flip-out lever need not be carried by the lower contact construction and need not be electrically connected to the lower contact of the fuse tube. It is common practice to have the `supporting means for the flip-out lever physically independent of the lower contact, and this practice may be followed if desired.

It is to be understood that the fuse tube need not be guided by means carried by the lower contact assembly but could be guided by other means as shown in Figure 10. Also, the ipper on fuse link extracting means need not be carried by the lower contact assembly but may be carried by other means as shown in Figure 11. Further, the collar on the tube need not be beveled but could be a collar which is rectangular in cross section as shown in Figure 12.

Referring to Figure 10 it will be seen that the fuse tube 41 is guided by means 42 formed as an integral projection or part of the door and the fuse tube, therefore, will be guided by means independent of the lower contact assembly 43.

In Figure 11 the guiding means 45 could be carried by the lower contact assembly 46 as shown in such figure, or could be carried by the door `as shown in Figure 10.

The ipper or fuse link extracting means 47 in Figure 11 is carried by a separate member 48 independent of the lower contact assembly 46. However, the flipper 47 is carried by the support or member 48. hereinabove mentioned, and the roller means 51 is guided by slots 52 formed in the member 48.

It is to be noted, at this point, that the guiding slots 53, for the roller means 54, may be formed in the lower contact assembly 43 as shown in Figure l0, or may be formed in a separate member as shown in Figure 11.

It is apparent that the lower restraining collar need not be Ibeveled but, as shown in Figure 12, such collar 55 on the fuse tube 56 may be rectangular in cross section. The roller means 57 is guided by slots 58 formed in the member 59 which may be a member like that shown in Figure l0 or in Figure 11. It is to be noted, however, that the slots or guiding grooves 58 slant downwardly in Figure l2 so that there will be a lateral thrust to the left on the roller means due to the downward pressure on the fuse tube.

It is to Ibe noted also as shown in Figures 13, 14 and 15 that the top or cap of the fuse tube may be expendable.

In Figures 13 and 14 it is intended that the fuse tube 60 be provided with an upper contact 61 against which the button or head 62 of the fuse link is clamped by a top or cap 63 formed of plastic, or other friable or easily 7 broken material. The lcap 63 is screwed on the upper contact 61 of the fuse tube 60;

The upper contact 6l has a pair of metallic pins 64 projecting from opposite sides thereof against which a pair of spring contact arms 65 bears. These contact arms are spaced apart as shown in Figure 14 so as to provide an unobstructed space through which the cap 63 is projected when the fuse blows. The Contact arms 65 are electrically connected ,to the upper stationary contact and thus form a part thereof.

The expendable cap may be made of metal, if desired, as shown in Figure l5. The expendable cap is indicated by the reference character 66 in Figure 15 and is provided with a thin portion or weakened portion 67 so that this weakened portion may be easily broken and blown olc by the pressure developed by the gases generated upon rupture or melting of the fuse link. Other means may be used for providing the weakened portion for the metal cap 66 or, in fact, for the plastic cap 63 if so desired. Both of these caps, the plastic cap and the metal cap, are screwed upon the upper contact of the fuse tube.

There is a direct cooperation between the expendable cap and the time delay means which is even more needed when an expendable cap is employed than when a permanently positioned cap is used.

In a permanently positioned cap where the upper end of the fuse tube is permanently closed, that is to say during the expulsion of the fuse link, there is a natural time delay due to the reaction downwardly or outwardly from the open end of the fuse tube. However, it sometimes happens that the fuse tubes are mounted either vertically or horizontally and the time delay still exists even when the fuse tube is mounted horizontally where the top is permanently closed.

However when an expendable cap is used the reaction is substantially the sarne at both the upper end of the fuse tube and the lower end of lthe fuse tube and there is not the natural time delay produced by the downward force exerted by, or due to, the blast of gases downwardly from the open end of the fuse tube. Instead there is, in the expendable cap type, a reaction produced both at the upper and the lower ends which are in opposite directions and the inherent time delay then does not exist.

Therefore it is even more imperative that kthe time delay means be'employed where an `expendable cap is used for there is no delay inherently due to the react-ion ofthe blast of gases.

It is to be understood that where an expendable cap or top for the fuse tube is used, that it is within the scope of this invention, where the fuse tube is mounted within a housing, to provide the housing with an expendable top portion also, or with a movable top portion, of any suitable type, to prevent the trapping of discharged gases within the housing.

Although the invention has been described in considerable detail, it is to be understood that such description is intended as illustrative and not limiting as the invention may be variously embodied and vis to be interpreted as claimed.

I claim:

l. A drop-out fuse construction comprising supporting means having upper and lower stationary contacts, a fuse tube having an upper end provided with an upper contact normally engaging the upper stationary contact and 'having a lower contact normally engaging the lower stationary Contact, a collar on said fuse tube adjacent its lower end, guiding means for slidably guiding said fuse tube downwardly, a fuse link within said fuse tube electrically joining the'upper and lower contacts of said fuse tube and projecting outwardly fromthe lower end of said fuse tube, a pivoted ip-out lever biased towards rocking motion for withdrawing any remaining portion =of said fuse link from said fuse tube upon rupture of said fuse link, said ilip-out lever having cam means, and

,fuse tube.

2. A drop-out fuse construction comprising supporting means having upper and lower stationary contacts, a fuse tube having an upper end provided with an upper contact normally engaging the upper stationary contact and lhaving a lower contact normally engaging the lower stationary contact, a collar on said fuse tube adjacent its lower end, guiding means for slidably guiding said fuse tube downwardly, a fuse link within said fuse tube electrically joining the upper and lower contacts of said fuse tube and projecting outwardly from the lower end of said fuse tube, a pivoted ilip-out lever biased towards rocking motion for withdrawing any remaining portion of said fuse li-nk from said fuse tube upon rupture of said fuse link, said iiip-out lever having cam means, restraining means normally engaging the collar of said fuse tube and guided by means adjacent the lower end of said fuse tube and arranged to move away from said fuse tube to release said fuse tube, and means operated by said flip-out lever and engaging the said restraining means for normally holding the restraining means in fuse tube restraining position and movable upon motion of said flip-out lever to allow said restraining `means to move away from restraining position for said fuse tube, said cam means having an extended fuse tube restraining portion normally engaging said restraining -means and restraining said fuse to provide a time delay.

3. A drop-out fuse construction comprising supporting means having upper and lower stationary contacts, a drop-out fuse tube having an upper end provided with an upper contact normally engaging the upper stationary contact and having a lower end and having a lower contact means normally engaging the lower stationary contact, guiding means for guiding said fuse tube downwardly, a fuse link within said fuse tube electrically joining the upper contact and lower contact means of said fuse tube and projecting outwardly from the lower end of said fuse tube, a biased pivoted iiip-out lever arranged to rock to release said fuse tube upon rupture of the fuse link, said fuse link passing around said flip-out lever, cam means operated by said flip-out lever, means having guiding slots, and restraining means guided by said guiding slots and normally held by said cam means in a position adjacent said fuse tube to restrain said fuse tube, and means carried by said fuse tube and normally engaged by said restraining means when said fuse tube is in service position.

4. A drop-out fuse construction comprising supporting means having upper and lower lstationary contacts, a drop-out fuse tube having an upper end provided with an upper contact normally engaging the upper stationary contact and having an open lower end and having a lower contact normally engaging the lower stationary contact, guiding means for guiding said fuse tube downwardly, a fuse link within said fuse tube electrically joining the upper and lower contacts of said fuse 'tube and projecting outwardly from the lower end of said fuse tube, a biased pivoted Hip-out lever arranged to rock to release said fuse tube upon rupture of the fuse link, said fuse link passing around said -ip-out lever, cam means operated by said flip-out lever, means having guiding slots, and tube restraining means guided by said guiding slots and normally held by said cam means in a position adjacent said fuse tube to restrain said fuse tube, and means carried by said fuse tube and normally engaged by said tube restraining means when said fuse tube is in service position, said cam means having a'n extended portion normally engaging said restraining means to provide a time delay.

5. A drop-out fuse construction comprising supporting means having an upper and a lower stationary contact, a downwardly slidable fuse tube having upper and lower contacts and having an open lower end, the upper and lower contacts of said fuse tube being no-rmally in engagement with the upper and lower stationary contacts, respectively, a fuse link within said fuse tube projecting from the lower open end of said fuse tube and normally electrically joining the upper and lower contacts of said fuse tube, a biased pivoted flip-out lever arranged to withdraw any remaining portion of said fuse link upon l rupture of said fuse link, said flip-out lever having cam means, said fuse tube having projecting means adjacent its lower end, and roller means normally engaging the projecting means on said fuse tube to restrain said fuse tube, said roller means being controlled by the cam portion of said flip-out lever and being normally held against releasing motion.

6. A drop-out fuse construction comprising supporting means having an upper and a lower stationary contact, :a downwardly slidable fuse tube having upper and lower contacts and having an open lower end, the upper and lower contacts of said fuse tube being normally in engagement with the upper and lower stationary contacts, respectively, a fuse link within said fuse tube projecting from the lower open end of said fuse tube and normally electrically joining the upper and lower contacts of said fuse tube, a biased, pivoted ilip-out lever arranged to withdraw |any remaining portion of said fuse link upon rupture of said fuse link, said flip-out lever having cam means, said fuse tube having projecting means adjacent its lower end, and guided roller means normally engaging the projecting means on said fuse tube to restrain said fuse tube, said roller means being controlled by the cam portion of said ilip-out lever and being normally held against releasing motion, said cam means having an extended portion normally engaging said roller means and restraining said fuse tube to provide a time delay.

7. A drop-out fuse construction comprising a casing having an upper stationary contact and Aa lower stationary contact, a slidable fuse tube positioned within said casing and having an upper end and having an upper contact and `a lower contact respectively engaging the upper and lower stationary contacts, said fuse tube having 'an open lower end, a beveled collar on said fuse tube adjacent the lower portion of said fuse tube, a fuse link within said fuse tube electrically joining the upper and lower contacts of said fuse tube, a flip-out lever spring biased towards tlip-out motion and restrained against llip-out motion by said fuse link and arranged to withdraw any remaining portion of said fuse link from said fuse tube upon rupture of said fuse link, said iiip-out lever having cam means, the lower contact of said fuse tube having guiding slots, a transverse pin provided with roller means for engaging the collar of said fuse tube to restrain said fuse tube against downward sliding motion, said roller means being adapted to engage said cam means, said pin being guided by said slots in the lower contact of said fuse tube and said roller means being held in fuse tube restraining position by the cam means of said ilip-out lever and being released for motion away from said fuse tube when said {lip-out lever executes llip-out motion.

8. A drop-out fuse construction comprising an upper stationary contact and a lower stationary Contact, a slidable fuse tube having an upper contact and a lower contact respectively engaging the upper and lower stationary contacts, Ia collar on said fuse tube adjacent the lower portion of said fuse tube, said collar being rectangular in cross section, a ruse link within said fuse tube electrically joining the upper and lower contacts or' said fuse tube, a ip-out lever spring biased towards llipout motion and restrained )against Hip-out motion by said fuse link and arranged to withdraw any remaining portion of said fuse link from said fuse tube upon rupture of said fuse link, said flip-out lever having cam means, means having downwardly extending guiding slots, a transverse pin provided with roller means for engaging the collar of said fuse tube to restrain said fuse tube against downward sliding motion, said roller means being adapted to engage said cam means, said pin being guided by said slots and said roller means being held in fuse tube restraining position by the cam means of said llip-out lever and being released for motion .away from said fuse tube when said flip-out lever executes flip-out motion.

9. A drop-out fuse construction lcomprising a casing having an upper stationary contact and a lower stationary contact, a slidable fuse tube having an upper contact and a lower contact respectively engaging the upper and lower stationary contacts, a beveled collar on said fuse tube adjacent the lower portion of said fuse tube, a fuse link within said fuse tube electrically joining the upper and lower contacts of said fuse tube, a ip-out lever spring biased towards llip-out motion and restrained against flipout motion by said fuse link and arranged to withdraw any remaining portion of said fuse link from said fuse tube upon rupture of said fuse link, said flip-out lever having cam means, means having guiding slots, a transverse pin provided with roller means for engaging the collar of said fuse tube to restrain said fuse tube against downward sliding motion, said roller means being adapted to engage said cam means, said pin being guided by said slots and said roller means being held in fuse tube restraining position by the cam means of said flip-out lever and being released for motion away from said fuse tube when said llip-out lever executes llip-out motion.

l0. A drop-out fuse construction comprising a casing, having an upper stationary contact and a lower stationary contact, a fuse tube having an upper end provided with an upper contact normally in engagement with the upper stationary contact, said fuse tube having a lower contact provided with guiding means for slidably guiding said fuse tube for downward sliding motion, said fuse tube having an open lower end, a fuse link within said fuse tube electrically joining the upper and lower contacts of said fuse tube and projecting outwardly from the lower open end of said fuse tube, said fuse tube having a collar adjacent its lower end, said collar having a beveled lower portion, roller means normally engaging said collar and holding said collar against downward motion to thereby normally restrain said fuse tube against downward sliding motion, said lower contact of the fuse tube having guiding slots for guiding said roller means, and a channel shaped, biased flip-out lever normally restrained against motion by said fuse link and having cam portions on opposite sides thereof engaging the said roller means and normally holding the roller means in fuse tube restraining position and releasing said roller means for motion away from said fuse tube upon rupture of said fuse link.

ll. A drop-out fuse construction comprising a casing having upper and lower stationary contacts, and having a door, a fuse tube slidably carried by said door, and having an upper contact normally engaging the upper stationary contact and having a lower contact, a fuse link within said fuse tube electrically connecting the upper contact of said fuse tube with the lower stationary contact, said upper contact of the fuse tube having a screw threaded cap, and said fuse link having a head adapted to be engaged by said screw cap to lock said fuse link in position, said fuse tube having projecting pins adjacent its lower end, stationary means supported from said door and provided with slots on opposite sides thereof for engagement with said projecting pins to prevent rotation of said fuse tube upon refusing and when the cap of said fuse is screwed into, or out of, position.

(References on following page) References Cited in the le of this patent UNITED STATES PATENTS Schultz et al NOV. 29, 1938 Schultz June 11, 1940 5 Schultz Feb. 11, 1941 12. Birkenmaier Mar, 18, 1941 Schultz Mar. 9, 1943 Link Oct. 12, 1943 Schultz July 1, 1947 Schultz Jan. l1, 1949 Schultz July 4, 1950 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,884,500 April 28, 1959 Georgev R. McCloud It is hereby certified that error appears in theprinted specification of' the above "numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 8, line 35, and column lO, line '74, after Hfuse'u insert Signed and sealed this 8th dey of' September 1959.

(SEAL) Attest:

KARL H. AXLINE l ROBERT C. WATSON Attesting Ofcer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF `CORRECTION Patent No. 2,884,500 April 28, 1959 George R McCloud It is herebT certified that error appears in the-printed specification of the above Inumbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 8, line 35, kand column l0, linz-:174, after "fuse" insert Signed and sealed this 8th day .of September 1959,.

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Ofcer Commissioner of Patents 

